Parallel-plate waveguides for terahertz-driven MeV electron bunch compression

Area of Science:

• Physics
• Engineering
• Applied Electromagnetics

Background:

• Femtosecond electron beams require precise manipulation for advanced applications.
• Strong-field terahertz (THz) pulses offer a promising tool for particle beam control.
• Existing methods for electron bunch compression face limitations in efficiency and field strength.

Purpose of the Study:

• To demonstrate the electromagnetic performance of a novel waveguide for femtosecond electron beam manipulation.
• To achieve significant compression of electron bunches using strong-field THz pulses.
• To present and evaluate a modified waveguide design for enhanced beam control.

Main Methods:

• Utilized an exponentially-tapered parallel-plate waveguide (PPWG) designed for dispersion-free operation.
• Employed electro-optic sampling (EOS) to measure peak electric fields in the THz interaction region.
• Investigated a modified shorted PPWG design for improved electron beam manipulation and reduced magnetic fields.

Main Results:

• Achieved peak THz fields of at least 300 kV/cm within the tapered PPWG structure.
• Demonstrated electron bunch compression by a factor of over 4 using 5 µJ of THz energy.
• Obtained a compressed electron bunch length of approximately 18 femtoseconds (fs) for a 2.5 MeV electron bunch.

Conclusions:

• The demonstrated tapered PPWG is effective for femtosecond electron beam bunch manipulation and compression.
• The modified shorted PPWG design offers advantages for beam control and reduced magnetic field effects.
• This work advances the capability of THz-driven particle accelerators and related technologies.